The invention relates to processes for eliminating contaminants from biological products by separation using anion-exchange membranes and to biological products cleaned up using these processes.
High demands are made of the purity of biological products, especially if they are to be used, for example, for pharmaceutical purposes. This is true especially if intraperitoneal or intravenous applications are contemplated. In this connection, especially viruses, endotoxins and nucleic acids, such as DNA, are of importance as possible contaminants. These contaminants are summarized as biological contaminants.
Contaminating viruses can be made harmless, for example, by chemical inactivation; WO 95/16 030 describes process variants which are customary in this context. Furthermore, removal by ultrafiltration is customary; for this purpose, for example, EP 0 302 949 discloses an ultrafiltration membrane having a specific pore geometry. Removal specifically of human immuno-deficiency virus (HIV) on non-porous ion-exchange materials is disclosed in EP 0 320 184. Endotoxins can be removed by treatment with a salt-containing detergent solution, as disclosed, for example, in WO 95/21 179. For the removal of endotoxins, furthermore, membranes derivatized in a special manner are proposed (WO 97/33 683). Nucleic acids can be removed by particulate anion exchangers, as described, for example, in J. Chromat. A, 658, pages 459-463 (1994).
WO 96/22 316 and WO 97/49 754 disclose polyamide-based adsorption membranes having improved properties. These improved separation materials may be synthesized by reacting the aminogroups of a polyamide with an amino-reactive compound or by reacting the carboxyl groups of a polyamide with a carboxyl-reactive compound, polymerizable groups being introduced into the abase, polymer. Additional amino groups or carboxyl groups can be introduced prior to the introduction of the polymerizable groups by reacting with diamines or dicarboxylic acids or dicarboxylic acid derivatives. Monomers can then be polymerized onto the said polymerizable groups. These monomers can comprise separation effectors; it is also possible to introduce separation effectors into the monomer units using known polymer-analogous reactions. With regard to the possible separation effectors and the preparation of adsorption membranes which comprise these separation effectors, reference is made to the abovementioned publications. The separation effectors mentioned in these publications also include cationic groups. The use of the anion-exchange membranes as disclosed in WO 96/22 316 and WO 97/49 754 for removing biological contaminants from biological products is the subject-matter of the present invention. For the inventive use, preference is given especially to anion-exchange membranes which are obtainable by reaction of a polyamide with a amino-reactive polymerizable compound and subsequent polymerization with monomers which comprise cationic groups, or into which cationic groups can be introduced in a polymer-analogous reaction.
These anion-exchange membranes can be constructed, for example, as flat membranes or as hollow-fibre membranes. Hollow-fibre membranes can be used in a xe2x80x9cdead endxe2x80x9d configuration or in xe2x80x9ccrossflowxe2x80x9d configuration. These embodiments and their preparation are known to those skilled in the art.
It has been found that, advantageously, using anion-exchange membranes disclosed in WO 96/22 316 and WO 97/49 754, the said contaminants can be removed from solutions. Thus it has been found that endotoxin can be removed not only from a buffer solution but also from a solution of proteins. It has further been found that DNA (HindIII fragments of DNA of phage xcex can be removed from protein. It has also been found that viruses can be removed from solutions, including viruses which can be removed only inadequately by known methods, for example by nanofiltration.
The invention relates to processes for the removal or depletion of biological contaminants, the sample to be cleaned up (biological product) being treated with an anion-exchange membrane, the said anion-exchange membrane being obtainable by reaction of a polyamide with an amino-reactive polymerizable compound and subsequent polymerization with monomers which comprise cationic groups, or into which cationic groups can be introduced in a polymer-analogous reaction.
The invention further relates to cleaned-up biological products obtainable by the process of the invention.